Encountered this by accident many years ago, the first I'd heard of Rustic Roads. Many are not quite this rustic.

RR51 - very much a favourite of people hereabouts as you know, and a handy dandy location. Get_Bent and I rode it with a chap who was riding a BIG Suzuki Cruiser, he really had no problems at all.

It is true that several of the RRs are just town streets, and are disappointing, but there are some really fun unpaved ones through forests. I enjoyed 91 a lot - it surprised me when we got into it (Rode it with Get_Bent on July 4th 2011).

Got up to RR109 and RR113 today. 113, being pretty new, still does not have signs. 109 could use some help as parts of them seem to be missing. The wind going up there was a bitch but riding some pretty decent "trails" in the Chimaquain-Nicolet National Forest made the trip up from Chicago worth it.

I rode about 300 cold, windy miles yesterday and grabbed 5 Rustic Roads. It was mostly paved, but did ride some gravel and dirt.
RR82
RR 106

RR 104

RR 22

RR 72

Five Rustic Roads in five separate counties. Although it was too cold and windy to stop and enjoy the scenery, it was very nice going through the White River marsh area, Horicon Marsh, and the Kettle Moraine area on the way back north.